Vitamin C: A Highly Effective Treatment for Colds

A recent and well-publicized review of vitamin C by the Cochrane Collaboration has resulted in much misguided discussion in the popular press (1).

There are important facts that emerge from the review. At least 30 controlled clinical trials (many double-blind and placebo-controlled) involving a total of over 11,000 participants have been conducted. Vitamin C in doses ranging from 200 mg to 2,000 mg per day (the dosage range used in a large majority of the studies) reduces the duration of colds by 7% for adults and 15% for children. The data indicates that there is a normal dose-response relationship. Vitamin C is more effective the higher the dose. The most effective doses are far more than 2,000 mg/day. Exclusion of higher-dose studies because they were not placebo controlled is not justified.

The effectiveness of vitamin C against colds could well provide a justification for the Food and Nutrition Board raise the RDA of vitamin C. The primary reason for reluctance to take this action is because it would, for most persons, require vitamin C supplementation or a plant-based diet, or both.

The results of a trial conducted in Japan have just been published (2). It is a double blind, 5-yr randomized controlled trial involving 439 participants. The supplemented groups received either 50 or 500 mg/day of vitamin C. The study indicates that vitamin C supplementation does indeed reduce the frequency of colds. The probability of suffering from 3 colds over the course of the study period was reduced by 66% in the group supplementing at 500 mg/day.

For decades, numerous reports from physicians have provided ample clinical confirmation about the effectiveness of vitamin C for treating the common cold (3-5). Orthomolecular physicians have worked with their patients to optimize the dose and have confirmed the conclusions reached by the authors of the Cochrane report that higher doses of vitamin C are more effective (6). They have concluded that patients will benefit by taking as much vitamin C as they can tolerate, and encourage patients to balance the benefits of fighting off a cold sooner with the drawback of intestinal discomforts. These discomforts are harmless and last at most for a few hours. Epidemiological studies associate long-term vitamin C supplementation with health benefits and increased longevity. A 23-year review of collected US poison control center annual reports (7) tells a remarkable and largely ignored story: vitamin C is extraordinarily safe.

We are confident that the RDA/DRI for vitamin C will eventually be raised. It is just a matter of time.

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